public class Test {
    public static void main(String[] args) {
        StringBuilder stringBuilder = new StringBuilder("hello");
        System.out.println(stringBuilder);

        stringBuilder.reverse();
        System.out.println(stringBuilder);


    }
    public static void main2(String[] args) {
        StringBuilder stringBuilder = new StringBuilder();
        for (int i = 0; i < 100; i++) {
            stringBuilder.append(i);
            stringBuilder.append("\n");
        }
        System.out.println(stringBuilder);
    }

    public static void main1(String[] args) {
        StringBuffer stringBuffer = new StringBuffer();
        for(int i=0;i<100;i++) {
            stringBuffer.append(i);
            stringBuffer.append(" ");
        }
        System.out.println(stringBuffer);
    }
}
